DLL封装MDI窗体(DLL)

一：新建DLL

library TestMDIDll;

{ Important note about DLL memory management: ShareMem must be the
first unit in your library's USES clause AND your project's (select
Project-View Source) USES clause if your DLL exports any procedures or
functions that pass strings as parameters or function results. This
applies to all strings passed to and from your DLL--even those that
are nested in records and classes. ShareMem is the interface unit to
the BORLNDMM.DLL shared memory manager, which must be deployed along
with your DLL. To avoid using BORLNDMM.DLL, pass string information
using PChar or ShortString parameters. }

uses
SysUtils,
Classes,
Forms,
Windows,
UDllMain in'UDllMain.pas'{frmDLLMain};

{$R *.res}
var
DllApplication: TApplication;
DllScreen:TScreen;

procedure ShowChild(ParentApplication: TApplication; ParentForm: TForm;ParentScreen:TScreen);export; stdcall;
var
frmDLLMain: TfrmDLLMain;
begin
Application:=ParentApplication;
screen:=ParentScreen;
frmDLLMain:=TfrmDLLMain.Create(ParentForm);
frmDLLMain.Show;
end;
procedure DLLUnloadProc(Reason: Integer); register;
begin
if Reason = DLL_PROCESS_DETACH thenbegin
Application:=DllApplication;
screen:=DllScreen;
end;
end;
exports
ShowChild ;

begin
DllApplication:=Application;
DllScreen:=screen;
DLLProc := @DLLUnloadProc;
end.

二：增加Form(UDllMain),修改Form.FormStyle=fsMDIChild

unit UDllMain;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs;

type
TfrmDLLMain =class(TForm)
procedure FormClose(Sender: TObject; var Action: TCloseAction);
private
{ Private declarations }
public
{ Public declarations }
end;

var
frmDLLMain: TfrmDLLMain;

implementation

{$R *.dfm}

procedure TfrmDLLMain.FormClose(Sender: TObject; var Action: TCloseAction);
begin
Action:=caFree;
end;

end.

三：新建项目，增加Uint(ULoadDll)，声明DLL

unit ULoadDll;

interface

uses Windows,SysUtils,Forms;
type
ShowMdiForm=procedure(ParentApplication: TApplication; ParentForm: TForm;ParentScreen:TScreen); stdcall;
var
RegisterDLLHandle:integer;
DllShowMdiForm:ShowMdiForm;

implementation

end.

四：主窗体Form.FormStyle=fsMDIForm

unit UTestMain;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, Menus;

type
TfrmMain =class(TForm)
MainMenu1: TMainMenu;
est1: TMenuItem;
procedure est1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
frmMain: TfrmMain;

implementation

uses ULoadDll;

{$R *.dfm}

procedure TfrmMain.est1Click(Sender: TObject);
begin
RegisterDLLHandle:=loadLibrary('TestMDIDll.dll');
if RegisterDLLHandle>0then @DllShowMdiForm:=getProcAddress(RegisterDLLHandle,'ShowChild');
if (@DllShowMdiForm<>nil) then
begin
if frmMain.MDIChildren[0].Caption='frmDLLMain'then
ShowMessage('1')
else
DllShowMdiForm(Application,Self,screen);
end;
end;

end.